There are numerous designs of puzzles belong to a family of the worldwide famous Rubik's cube. For example, there are known puzzles of this type invented by Erno Rubik and disclosed in the Hungarian Patent HU No. 170062 and U.S. Pat. No. 4,378,116 “A Spatial Logical Toy”. Such puzzles comprise elements assembled with spaced inside an intersecting axes member thus forms a 3D shaped body like a three layers cube mainly. The elements form groups of elements each of them have a possibility to rotate around the corresponding axis of the intersecting axes member. The mentioned designs relatively are not simple due to the necessity of the intersecting axes member and, therefore, are costly.
By now, the attraction of such puzzles is practically exhausted because all assembling algorithms are well-known and described, thus, the puzzles attraction is increased in an extensive way by increasing the number of layers. That led to further increasing of the design complexity and cost correspondingly.
There are known puzzles of the mentioned type that have a simplified design, for example, described in the PCT Patent Application WO83/01203 “Three-Dimensional Geometric Puzzle”. Such design disclosed a 3D puzzle that comprises only elements form a various 3D shaped body, without the intersecting axes member. Each element has means cooperating with all adjacent elements permitting the sliding of the elements relative to the adjacent elements along an imaginary spherical surface. The means are made as a tongue and groove inter-engagement structure. The puzzle assembling provided by the positioning of each element with the following snapping into place by external pressure. The mentioned 3D puzzle has the same difficulty level during assembling the puzzle like the mentioned above Spatial Logic Toy as well as the assembling algorithms, and therefore, has the same level of the attraction.
Despite the design of the 3D puzzle according to the PCT Patent Application WO83/01203 is more simple, additional problems are arisen. Because the puzzle assembled by applying external pressure, there must be enough clearance at the tongue and groove inter-engagement structure, otherwise some of elements could be destroyed. But such clearance between two adjacent elements summarized with clearances of other elements, that form the group of element which is currently rotated, led to the loss of the shape stability of the group and embarrassed the rotation in respect to other elements.
There is also known puzzle, that provides increasing the puzzle attraction by the possibility to be open if puzzle elements are arranged in the correct order. For example, the U.S. Pat. No. 5,452,895 “Three Dimensional Rotating Puzzle That Open” discloses a spherical puzzle comprises eight fife-sided elements and thirty six-sided elements which are connected by means of a locking rail system that allows all of the elements to be shiftable around the three equatorial planes of the puzzle. According to the mentioned patent the puzzle is hollow inside and can be opened by removing one of the six-sided elements if the elements are arranged in the correct order.
But, despite to the presence of a new feature like opening the puzzle, the attraction of the puzzle in comparison with the mentioned above puzzles is the same or less, depending on the goal of the assembling. If the goal of the puzzle according the U.S. Pat. No. 5,452,895 is the arranging all of the elements in the correct order defined by the colored patterns, the difficulty level will be the same. And, if the goal of the puzzle is the puzzle opening by removing one of the six-sided elements, the difficulty level will be less. In fact, it is evident that the necessity condition for such opening is the arrangement of the element which is opened and the adjacent elements only, in the correct order, all other elements could be arranged at any order. There are a lot of combinations of the arranged elements allowed to open the puzzle that decrease the puzzle difficulty level.
And more, the puzzle design is not simple and the puzzle comprises the small parts like removable rail, which is flush-mounted into the corresponding five-sided element. It will be difficult to catch that removable rail due to the friction; otherwise, if the corresponding clearance will be increased, the removable rail can fall out of the puzzle during the play and lost. The last circumstance is very dangerous if such small part would be swallowed by small-age children.
The main problem of all known three-dimensional puzzles is that all designs can not resolve the contradiction between the tendency to increase the attraction of the puzzle from one hand and the design simplification from the other hand simultaneously.
Therefore, it would be generally desirable to provide a reliable, low cost design of the three-dimensional puzzle that is not complicated and at the same time more attractive in comparison with known 3D puzzles, thus overcome mentioned problems.